The NFL draft begins Thursday, and the Broncos are in the market for a young quarterback to develop under free-agent signee Case Keenum. Denver currently holds the No. 5 overall pick, and eight selections in the first five rounds. Here’s a look at the top prospects available.

TOP QUARTERBACKS

Sam DarnoldHeight/weight: 6-foot-3, 220 poundsSchool: USC2017 stats: 63.1 completion percentage, 4,143 yards, 26 touchdowns, 13 interceptions, 148.1 quarterback ratingAnalysis: Darnold is generally regarded as the biggest “sure thing” at quarterback in this draft, thanks to his physical tools, intelligence and poise. He burst onto the national scene as a redshirt freshman in 2016, reading the field and zipping throws into tight windows during an instant-classic Rose Bowl victory over Penn State. That made him the most-hyped player in the country entering last season, expectations he did not quite live up to. His biggest issue is taking care of the football, as he threw 13 interceptions and lost nine fumbles in 2017 and tossed 20 picks over his final 20 college games.

Josh RosenHeight/weight: 6-foot-4, 225 poundsSchool: UCLA2017 stats: 62.2 completion percentage, 3,756 yards, 26 touchdowns, 10 interceptions, 147 quarterback ratingAnalysis: Rosen has the sharpest throwing mechanics and footwork in this draft, resulting in some picture-perfect passed. But he was banged up at times throughout his college career and is less-than-mobile. Rosen is intelligent and unafraid to speak his mind, but some have questioned his openness to coaching, his leadership and his variety of interests outside of football.

Josh Allen Height/weight: 6-foot-5, 237 poundsSchool: Wyoming2017 stats: 56.3 completion percentage, 1,812 yards, 16 touchdowns, six interceptions, 127.8 quarterback ratingAnalysis: Allen is probably the quarterback that physically most reminds John Elway of, well, himself. But Allen is also the draft’s biggest wild card. He has an ideal frame and fantastic arm strength, but there are massive concerns about his accuracy while playing against Mountain West competition. Some of those troubles are the result of poor decision-making, but some can be attributed to the football version of “hero ball.”

Baker MayfieldHeight/weight: 6-foot-1, 215 poundsSchool: Oklahoma2017 stats: 70.5 completion percentage, 4,627 yards, 43 touchdowns, six interceptions, 198.9 quarterback ratingAnalysis: Mayfield is one of the most improbable college football success stories in recent memory, vaulting from walking on at Texas Tech to becoming a Heisman winner. Mayfield was one of college football’s most recognizable players because of his fiery demeanor to complement his gaudy stats. He is accurate on short, intermediate and deep routes and can scramble out of trouble, though sometimes he defaulted to throwing off his back foot when pressure arrived. His size and playing in a spread scheme will be knocks against him. Some teams could view his demeanor as too cocky to be the face of a franchise.

Lamar JacksonHeight/weight: 6-foot-3, 200 poundsSchool: Louisville2017 stats: 59.1 completion percentage, 3,660 yards, 27 touchdowns, 10 interceptions, 146.6 quarterback ratingAnalysis: The 2016 Heisman winner is an electric dual-threat playmaker, drawing comparisons to a young Michael Vick. But the team that drafts him would likely need to mold their offensive scheme around Jackson, allowing him to unleash that dangerous athleticism. His small build is a concern, as is his lack of accuracy compared to other prospects.

Mason RudolphHeight/weight: 6-foot-5, 235 poundsSchool: Oklahoma State2017 stats: 65 completion percentage, 4,904 yards, 37 touchdowns, nine interceptions, 170.6 quarterback ratingAnalysis: Rudolph boasts ideal size and has been praised for his intelligence and maturity. But he also draws the “system quarterback” label, as Oklahoma State’s spread offense did not require him to go through a huge bevy of progressions. Though Rudolph has terrific touch on his deep ball, he lacks zip on other throws.

QUARTERBACKS DRAFTED BY BRONCOS DURING JOHN ELWAY’S GM TENURE

Justin Edmonds, Getty Images

Brock Osweiler (17) watches as Trevor Siemian warms up before the Broncos’ loss to the New York Giants.

Gina Mizell covers the Denver Nuggets for The Denver Post. She joined The Post in September 2017, after 3 1/2 years covering Oregon State football for The Oregonian in Portland. She was named the 2016 Oregon Sportswriter of the Year by the National Sports Media Association. She was the Oklahoma State football beat reporter for The Oklahoman from 2011-14 and a sports reporter/columnist for The Beaumont (Texas) Enterprise from 2010-11. She is a 2010 graduate of the Walter Cronkite School of Journalism and Mass Communication at Arizona State University.